Low temperature resistant resin composition and method for making same



Patented a... 17, 1945 UNITED]: STATES PATENT OFFICE -Low TEMPERATURE. RESISTANT RESIN COMPOSITION'AND METHOD FOR MAK- ING SAME Addeline' J. McGillicuddy, Spokane, Wash, .as- 3 signor of one-half to G. A. Kjosness, Spokane, Wash., and one-fifth, to Bennett H. Levenson Washington, D. .C.

No Drawing. Application August 21,1941,

' Serial No. 407,821

4 Claims. (Cl. 260-36) This invention relates to the art of plastic resinous compositions. More particularly it pertains to resins of synthetic origin, embracing among its features novelty of product and method of preparing the same.

The potentialities of plastics 'or synthetic resinous materials withrespect to new adaptations and modifications are generally conceded to be of substantially unlimited extent. In this connection, a vast amount of investigational work has been performed for the purpose of obviating the dependency of thiscountry on natural matebe generically referred to as polyvinyl chloride containing, resins.

This propensity to brittleness or cracking is more apparent as the freezing temperature is ap- 'proached and becomes aggravated with a temperature decrease to values substantially below C.

rials with respect to which it is not self-sufficient,

diversified properties ranging from substantial rigidity to rubber-like flexibility, the prevailing characteristics being determined by a number of factors in addition to the fundamental substances or reactants involved in the polymerized composition. Among'the-more important of such factors are the type and quantity of plasticizers utilized. For example the flexibility, resiliency and general rubber-like properties of sheet or film material comprising a vinyl chloride-vinyl acetate copolymer, such as has been available under the name of Viny'lite Series V resins, is now known to be attributable insubstantial degree to the softening effect of the comparatively large 'plasticizer content. i

Notwithstanding the plasticizer' content inpoiyvinyl resin type products, they are known to manifest a tendency toward brittleness and/or cracking, which is especially apparent in the case of articles made from compositions containing polymerized vinyl halides. Illustrative of the halide resins particularly susceptible to this objectional tendency are the polyvinylchlorides, the copolymer of vinyl chloride and vinyl acetate, and other polymerizates or polymerizate mixtures containing polyvin l chloride, such as the mixed polymerizate of polyvinyl chloride and acrylic acid esters. In thefurther considerationgiven hereinbelow to this type of substances, they may or 32 F. It is applicable even in the case of the highly plasticized polyvinyl resins such as the normally resilient, flexible, rubber-like sheets or films above referred to, becoming particularly noticeable at low temperatures by diminution in plasticity, resiliency and the like; with progressively lower temperatures, the pliability and resiliency merges into a perceptible stlfiness and at temperatures approximating that ofdry ice,

-1l0 F., the formerly resilient rubber-like sheet or film may be fractured or shattered through impact or shock.

Attempts to obviate the brittleness and/or cracking tendency of polyvinyl resins have been based upon the treatmentof the dry or substantially polymerized material as distinguished from the plasticlzed article. Instead of calenderirig the polymerized resinous composition in the presence of a solvent or plasticizing agent, the My material has been subjected to rolling, as into the form of a thin sheet, while stretching the sheet in the direction of the rolling operation. Under such conditions of treatment, polymerized vinyl chloride type resins have allegedly shown a substantial brittleness reduction, in a direction at'right angles to that in which the stretch was applied.

By resorting to a dual stretch treatment through the application of tension to the sheet being formed, bothin the direction of rolling operation and at right angles thereto, in the presence of heat the aforesaid brittleness has, according to assertions, been reduced in all directions.

f It has further been suggested inconnection with this tensioning or stretching treatment that the addition during'the rolling operationto the dry polymerizates in their hot plastic state of small quantities of substances, characterized asemulsifying agents or low molecular weight lubricants under normal conditions functioning in the nature of lubricants, adhesives or binding agents, will increase the strength of the thin sheets or foils produced; this is in the nature of a slight plasticization during the tensioningtreatment. Included among such emulsifying or lubricating type materials'are mentioned various alcohols of the mono and poiyhydric type illustrated by octa- ,decyl alcohol, stearyl alcohol, oleyi alcohol, wool lat alcohol, glycerine, and glycerine ether alcohol; other designated types of materials include fled by stearic acid ethanol amide and stearic acid ethanol ester. The indications are that'while quantities approximating -1% of the polymerizate will provide reduction in brittleness proportions, up to 540% oi'the polymerizate will actually increase the brittlenessot the product.

As above stated, the. degree of rigidity, flexi- I bility and resiliency in articles formed from poly-.

merizedresins is materially "influenced by the proportion and'character of the plasticizlng agent, which in accordance with the usual practice is supplied-during the calendering treatment-the I greater, the plasticizer content, the more flexible and pliable the product. To provide desirable softness,-'oils are utilized in the calendaring treatment as plasticizing agents. Notwithstanding the inclusion of such plasticizing or softening-agents,

the tendency toward brittleness and cracking.

has been revealed as an inherent property of articles made 'from plasticized polymerized vinyl resins, especially of the polyvinyl chloride type.

'It is an object of this invention to obviate the undesirable characteristics in resinous compositions hereinabove described.

An additional object is to obtain a synthetic plastic composition which retains its normal properties and characteristics at substantially low temperatures. 7

Another object is the obtention of articles formed from polymerized vinyl resins in which their normal degree of resiliency or flexibility is from the plasticized copolymerizate oi vinyl chloride and vinyl acetate which retain their resiliency, flexibility and elasticity at temperatures as low as approximately. -110 F.

j .An. important object is to devise novel methods for producing plasticized resinous compositions, especially -*of the polyvinyl chloride type havingthe above described attributes.

Other-objects, advantages, and featuresof my invention will become apparent from the following description which is to be treated as illustrative and not limitative.

Within the scope of my invention, ithas been found that such tendency toward a change from the initial brittleness orcracking properties of resinous materials can be obviated by appropriate treatment of the polymerizate with a suitable -substance.- Thus, by way of illustration it has been determined that polymerized and plasticized polyvinyl resins may beefiectively treated with a reagent of the type above designated as lubri-.

cants to substantially remove any inclination toward cracking or brittleness, as a result of temperature decrease for exai'ii'ple; and to minimize the prevailing or inherent brittleness oi the resin product. i

U Preferably the fiso-called lubrican .reagents should be essentially inert to the resin and not have any substantial superficial effect, such as a solvent or chemical reaction thereon; however,

some such effect in small degree will not- 'neces-.

'sarily preclude a reagent from the scope of this" invention.

Substances that have in general been found to'function .eflectively comprise animal and vege- I 2,378,699 the fatty acid amidesand amide esters exemplitable oils and fats or esters, such substances being desirably relatively inert toward the res ipous composition; included within this contem-= plation are compatible mixtures of such 'suostances. While these lubricant reagents may be in liquid or solid state, the former is preferred especially from the standpoint of facility in treatment. Desirably the oil should be of the nondryingvariety although semi-drying oils may 10 provide beneficial results. Illustrative oi. animal and vegetable oils and esters which have been.

shown to be within the purview of the invention are neats' foot oil, olive oil, castor oil, fatty acid glycerides, inclusive of glyceride mixtures exemplified by "Crisco," lard, etc. I

Also operative within the purview of the invention are chemical substances exemplified by alcohols of the mono and polyhydric typ such -as ethyl alcohol and -glycerine, although these substances may notbe quite as effective or satisfactory as the oils or esters of the type above indicated. ,For' example, tests performed on the copolymer of vinyl chloride and vinyl acetate in 1 flexible sheet form with ethyl alcohol reveal an improved resistance to cracking, but the inherent flexibility of the sheet was not benefited. -As for glycerine, it likewise improved the resistance to cracking-tendency at low temperatures and had no apparent detrimental effect on resiliency or flexibility; however a tendency to develop turbidity in the resin was revealed.

A preferred embodiment of the invention is predicated upon the use of mineral oils, desirably such as are essentially free from paramn or asphaltic residues. Particularly optimum results are obtained fromthe use of refined, high-boiling distillates which satisfy the conventional de ignation ,or interpretation given to liquid petrolatum" or mineral oil," this substance being free from paraflin content or at least does not yield paraffin.

The procedural embodiment of the invention is based upon the surface contact or exposure of the resin to the. lubricant reagent utilized. While it is not intended to be restricted to any theory of operation, it is believed that some form of association, possibly in the nature of an impregnation phenomenon may take place between the reagent and the resinous composition, even though the latter has been plasticized.

Optimum conditions, of operation are considered to be at temperatures in excess of normal I oraverage values prevailing at atmospheric conditions. Especially adaptable and extremely suit- 55-able results have been attained by heating the polymerized and fplasticized. resinous composito the pointipi substantially incipient soften- .i g, although for most expedient operation the temperature should not attain a. degree at which the material alters its structural character. Subsequent to this heating treatment, the composition is advantageously inserted in a [bath of suitable lubricant reagent which may be at-normal v atmospheric temperature. The time for such mit of a reasonable contact in order 'to attain a desired effect upon the characteristics of the believed to beat least in part dependent upon I By wayofv example, illustrative both with still of substantial temperature.

respect to resin and reagent, which has afforded entirely satisfactory results inobviatin the 'cracking and brittleness tendency of polyvinylchloridetype resins, even at extremely low temperatures, and has improved the inherent .resiliency and flexibilitmwhile in no manner affecting the desirable properties of transparency or translucency, the following is set forth. The plasticized copolymerizate of vinyl chloride and vinyl acetate available in film or sheet formand impresslvely analogous to sheet or film rubber with respect to resiliency and general properties, is

-' the subject example; this resin composition is available in transparent as well as semi-trans;

parent or translucent form under the trade designation of fVinylite "V.

. In accordancewith the preferred procedural embodiment, this Vinylite is subjected to a heat acter of the resin and the rate at which it is brought to maximum temperature. Inthe case of sheet Vinylite V heated to approximately time interval of exposure to this low temperature-for as much as six hours-the Vinylite is removed from thelow temperature zone of perature treatment is not a prerequisite to the obtention of the product having the desired properties, and. serves primarily as an expedient test of the material, it is believed to actually improve the non-cracking and non-brittleness characteristics of the product at substantially low temperatures.

It has moreover been found that when sheets ":of material, treated in accordance with the present invention, are laminated, the improved results are embraced by the laminated product without sacrificing any of'the prior art features obtainable fromlamination. Similarly the inclusion of various perfecting ingredients durin I the course of preparing the resinous composition 230*FQ-2420? F., a half-hour of suchttreatment isquite satisfactory.

Upon completion .of the heating step, the resinliquid petrolatum at'atmospherlc temperature. The time of such immersion maybe varied behours where atmospheric cooling in the lbath is permitted. An expedient time is approximately tween wide 'limits,.from a few-minutes to several thirtyminutesalthough this is subject to varia- I tion withinthe skill of the operator.

Upon completion of this primary immersion -in the liquid petrolatum the Vinylitef is removed therefrom and desirably surface cleaned of all'superflcial oil. The product thus attained manifests the improved attributes relative to resiliency or softness? and resistance to cracking and brittleness, even at temperatures as low asapproximately '-110 F., correspondlng with the temperature of'solid CO2.

However to effectively control the oil content believed to result from impregnation, it has-been found desirable to subject the Vinylite" .to a

second heat treatment along the line's-of the first andfollowinggenerally the same range of tem- .perature conditions and time interval; Upon removal from the heating zone, the presence of superficial oil is again apparent, and it is merely necessary to againresort-to the aforementioned cleaningflstep to wipe the material dr of any surface signs 'of liquid. It is believed that this second heating treatment, which may be referred to as the tempering step, functions in the ca pacity ofa quantitative reagent control, thereby obviating the inclusion of excessive quantities of mineral oil, for example, within the resinous composition.

- Upon completion of this second cleaning step,

the resin may bepermitted to cool down to normal atmospheric conditions, and manifests the above referred to improved properties. In lieu of such gradual cooling however, the treated Vinylite may be subjected to extremely low temperatures as by direct contact with solid car- 1 bon dioxide which is at approximately -,-1l0 F.,

This frigid contact may follow, promptly upon the second cleaning step and while the .Yinylitef is. After a material does not in any material manner affect the adapt- '80 oils material is immersed in a bath of so-called with the present invention.

. It is apparent-from the scope of the invention that the plastic composition attainable in accordance therewith makes possible the adaptation of polyvinyl resins and analogous materials to a wide field of usage under extreme tempera- .ture conditions not heretofore expedient.-

While a preferred embodiment of treatment invalves heating the resinou composition prior to immersion in the reagent bath at substantially atmospheric temperatures, this procedure is subject to substantial variation within the purview of the invention. Effective results may alternatively be attained through submerging the resin in a heated reagent, the temperature of the reagent being below that which-will tend to distort the. shape or physical characteristics of the material, such as its sheet form, resiliency, etc. Similarly the resin may be heated while immersed in the reagent.

Where treatment is with a reagent having the -physical state of Crisco, undernormal atmospheric conditions, the heated resinmay be coated with.- 'the fat or' the resin may be heated in the presence thereof; It will be noted that the comparatively high temperature resorted to in heating the resinwili iluidize the fat, and therefore, after a brief time interval, the treatment hecomes equivalent to immersion in oil.

1 It should be noted that a distinct improvement in the characteristics of the polyvinyl resin may .be attained even under substantial atmospheric conditions, but the time necessary to attain any material-resistance to cracking will be substan tially in excess of that required at higher temperatures. However, some definite improvement in the resin is attainable merely through the expedient of appropriate surface coating; thus sheet Viny1ite" which has-had mineral oil rubbed .on its surfaceand then wiped clean has manifested some element of resistance to cracking at low temperature, although by no means as effec tively as that attained in accordance with optimum. procedure hereinabove described.

Thus it, is within the contemplation of the invention to treat the plastic composition with the reagent in any manner facilitating an expedient contact to attain the desired results, and such variations of procedure will be apparent to one versed in the artwithout departing from the invention herein.

While the exemplary procedure above set forth has been directed to the treatment of the flexible,

rubber-like sheet form of the Vinylitef copoly mer or vinyl chloride and vinyl acetate, it is similarly applicable to other physical forms of the resin. The performance of tests. in accordance with the above description, on resinous articles, especially 'of the polyvinyl chloride'containing typ manifesting considerable physical distincance-with the preferred embodimentsv of both composition and method, it is apparent that many variations and modifications both as to shaped article-ofplastioized polyvinyl chloride resin which comprises heating said resin, immersin: the heated resin' in a mineral oil substantially freefrom paraffin, removing said resin from the oil, freeing the resin from surface traces of oil, reheating the resin, again removing. oil from the surface of said resin and subjecting the resin to. a cooling treatment.

2. The, method of substantially obviating the" cracking tendency at temperatures substantially below freezing and reducing brittleness in a shaped article of a conjoint polymer of vinyl chic ride andvinyl acetate resin which comprises heating said resin, immersing the heated resinin -tions from the flexible sheet form produced sinijoint polymer of vinyl chloride and vinyl acetate,

liquid petrolatum, removing said resin from the oil, freeing the resin from surface traces of oil,

reheating the resin, and again'removingoilifrom the surface of said resin.

. a. 'm method of substantiall obviating the cracking tendencyat temperatures substantially below freezing and reducing brittleness in a shaped article of a rubber-like-plasticmer conwhich comprises immersing said article in liquid product and procedural details andsteps maybe made without departing from the scope of equivalents within the purview and spirit of this invention as defined in the following claims:

Having thus set forth my invention, I claim:

1. The method of substantially obviating the cracking tendency at temperatures substantially below freezing and reducing. brittlenessin a petrol'atum' while maintaining the temperature at the surface of thearticle at that of substantially incipient softening and belowthat which alters the structural character of the article, and removing superficial oil adhering to the surface of said article.

4. A shaped article position prepared by the method of claim 3.

' annnmmg J, 'ir drmrcunnr.

of plasticizedresinous com- H 

